System and method for diluting vapor and generating electricity

ABSTRACT

A system and method for converting hazardous waste vapors into a renewable energy source is disclosed. The system comprises a feeding system operatively coupled to a combustion system. The feeding system includes a vapor byproduct source capable of producing hydrocarbon vapors and a means for separating any liquids or particulates from the hydrocarbon vapor to create a purified vapor. The combustion system includes a compressor operable to pressurize the purified vapor to a select pressure range, a means for enriching the purified vapor with a select percentage of natural gas to form a fuel mixture, and a generator operable for converting the combined fuel mixture into electricity. Optionally, the combustion system may utilize a microturbine in combination with a fuel storage system, eductor, and a calorimeter and density meter to ensure maximum energy efficiency based on a select input range for fuel composition and pressure.

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.63/330,566 filed Apr. 13, 2022. The entire contents of the aboveapplication are hereby incorporated by reference as though fully setforth herein.

FIELD

The present application relates to the field of vapor recovery systems.More specifically, the present invention relates to systems forconverting recoverable vapors into renewable energy.

BACKGROUND

As a result of the global demand for trading and exchanging crude oiland its derivatives, like gasoline, these commodities are often storedbefore being transported from one place to another or used. Duringstorage, gases from the liquid oil separate and rise to the top formingvapors made of volatile organic compounds (“VOC”), which are alsocommonly referred to as “fugitive emissions.” In the case of crude oil,these gases largely are made from methane, which is harmful to theenvironment. In order to control the emissions of these gases, a varietyof systems have been developed to dispose of these emissions, includingsystems incorporating a flare, vapor recovery units (“VRUs”), or vaporcombustion units (“VCUs”).

VRUs utilize a carbon bed and blowers as a means of recovery forGasoline/Transmix, but these systems have several drawbacks. VRUs createmaintenance expenses as the carbon beds have to be replenished on aroutine 1-2 year interval. VRUs utilize a knockout pot, blowers,multiple pumps, and extensive piping arrangement for operation. VRUs areinefficient and typically provide minimal volume return based on thethroughput of loading (for example, 1000 gallons were transferred and 1gallon of product was recovered by means of VRU with Carbon Bed). As aresult, VRUs are slowly being serviced out and replaced with VCUs.

VCUs provide 99.9% destruction of VOCs but still create harmfulemissions and do not include a mechanism for converting these wastebyproducts into renewable energy. VCUs traditionally were developed offpropane and natural gas and due to newer CO/CO2 emissions requirementswill be utilizing natural gas only. VCUs utilize a smaller ratio ofnatural gas (20-30% methane) to vapor to dilute the contaminants foundin vapor. The combustion happens in an atmospheric state inside thevapor combustion stack. VCUs operate intermittently, so only whenloading, and therefore use significant natural gas for intermittentstartup/shutdown. VCUs for truck or rail racks inject natural gas at theupstream point of combustion, and for the marine loading cases, theyinject at both the point of loading and combustion. VCUs combust naturalgas mixed with vapor in an atmospheric state using a fresh source ofambient oxygen by means of an induction fan into the stack. As a result,these VCUs produce large quantities of CO and CO2 emissions with nomeans of after-treatment or means of capturing nitrogen or sulfurspecies.

While VCUs and VRUs have minimized harmful emissions when compared toprior alternatives, there is always a need for systems that furtherreduce pollution and increase energy efficiencies.

BRIEF SUMMARY OF THE INVENTION

It is the object of this invention to provide a system that convertshazardous vapors into a renewable energy source while simultaneouslylowering harmful emissions. The system comprises a feeding systemoperatively coupled to a combustion system. The feeding system includesa vapor byproduct source capable of producing hydrocarbon vapors and ameans for separating any liquids or particulates from the hydrocarbonvapor to create a purified vapor. The combustion system includes acompressor operable to pressurize the purified vapor to a selectpressure range, a means for enriching the purified vapor with a selectpercentage of natural gas to form a fuel mixture, and a generatoroperable for converting the combined fuel mixture into electricity. Thecombustion system may utilize a microturbine as a generator incombination with a fuel storage system, eductor, and a calorimeter anddensity meter to ensure maximum efficiency while using the microturbinebased on select input ranges for fuel composition and pressure.

In an alternative embodiment, the system includes a heat recovery systemcapable of capturing and converting exhaust gases from the generatorinto renewable energy using, for example, a heat pump and a generator.Optionally, a continuous emission monitoring system analyzer may be usedto analyze exhaust emissions from the generators of the system to ensurecompliance with environmental emission standards.

In an alternative embodiment, a method for converting hydrocarbon vaporsinto renewable energy is disclosed. The method comprises the steps ofproducing a hydrocarbon vapor from a vapor byproduct source, separatingliquids and particulates from the hydrocarbon vapor to create a purifiedvapor, compressing the purified vapor to a select pressure range,enriching the purified vapor with a select percentage of natural gas toform a combined fuel mixture, and converting the fuel mixture intoelectricity.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features, and advantages of theinvention are apparent from the following detailed description taken inconjunction with the accompanying drawings in which like parts are givenlike reference numerals and, wherein:

FIG. 1 is schematic view of a system for converting recoverable vaporsinto electricity in accordance with an embodiment of the presentinvention.

FIG. 2 is a table showing electricity generated from recoverable vaporsusing the embodiments of the present invention.

The images in the drawings are simplified for illustrative purposes andare not depicted to scale. Within the descriptions of the figures,similar elements are provided similar names and reference numerals asthose of the previous figure(s). The specific numerals assigned to theelements are provided solely to aid in the description and are not meantto imply any limitations (structural or functional) on the invention.

The appended drawings illustrate exemplary configurations of theinvention and, as such, should not be considered as limiting the scopeof the invention that may admit to other equally effectiveconfigurations. It is contemplated that features of one configurationmay be beneficially incorporated in other configurations without furtherrecitation.

DETAILED DESCRIPTION

Turning to FIG. 1 , a flow diagram of a first embodiment of the vaporrecovery system 10 is disclosed. Similar to other recovery systems knownin the art, e.g. VCUs and VRUs, the disclosed vapor recovery system 10includes a feeding system 15 that includes a vapor byproduct source 20that is configured to store hydrocarbon vapors or VOCs. These vaporbyproduct sources 20 can take many forms, including for example, aloading rack used for loading/offloading from a barge, railcar or ship,or alternatively, an offshore loading platform using a very large crudecarrier (VLCC). Other examples include the saturated hydrocarbons foundin ballast water for bulk liquid transport via ship or barge. Theballast water has saturated hydrocarbons that is typically degassed andflared prior to returning back to a ship or barge. An additional examplewould be the storage of light hydrocarbons in salt dome caverns by useof brine displacement. The brine has saturated hydrocarbons that istypically degassed and flared prior to returning brine back to the brineponds. An additional example would be the vapor space on geodesic domesof stabilized crude storage tanks or any API Tank needing to reducegreenhouse gas emissions. An additional example would be the vapor foundinside a Fixed Roof or an Internal Floating Roof of an API StorageTanks.

The hydrocarbon vapors or VOCs from these vapor byproduct sources 20 arethen fed into a gas/liquid separator 30, such as a knock-out pot ordegasser, that is configured to remove bulk liquids and particles fromthe vapor gas to form a purified vapor.

Unlike preexisting systems, the next phase of the vapor recovery system10 describes the combustion system 40 and illustrates how the purifiedvapors are converted into renewable energy. The combustion system 40includes a compressor 60, a natural gas supply 70, and a generator 80.The combustion system 40 may require a blower 50 to pump the purifiedvapors to the compressor 60.

As shown in FIG. 1 , the purified vapors from the gas/liquid separator30 are fed into the blower 50, which pumps the purified vapor gas to thecompressor 60. The compressor 60 is equipped with a motor 90 operable tocompress the purified vapor gas to 50-75 psig to eliminate any heavyhydrocarbons that could potentially have a scavenging sulfur andnitrogen species not suitable for combustion and emissions. The purifiedvapors will be compressed using either a positive displacementcompressor or liquid ring vacuum pump depending on system flow rates.For example, a suction scrubber, positive displacement compressor, andcoalescing filter are required for high flow rate scenarios. Conversely,a liquid ring vacuum pump, liquid seal pot, heat exchanger,recirculating pump, cooling water, and coalescing filter are requiredfor lower flow rate scenarios. This component of compression of fugitiveemissions removes a significant amount of the heavier hydrocarbon chainsfound in fugitive emissions. This compression will range from 50-75 psigdepending on geographical location, selected hydrocarbon or bulk liquid,bulk liquid temperature, loading method, and ambient temperature. Someof the heavy hydrocarbons and any humidity will change phase to a liquidand sent back to the knock out pot via a mechanical coalescer 35. Aftercompression, a steady state continuous operation will occur by means ofa storage system 85.

For purposes of the disclosed system 10, any generator 80 that operateson a combustible fuel mixture to generate electricity can be used.However, the preferred form of a generator 80 is a microturbine. Thepreferred microturbine requires inlet pressures between 75-85 psig and afuel mixture that includes 30-45% natural gas for combustion. To ensureefficient destruction of VOCs using the microturbines, the system 10 mayemploy testing at certain nodes.

For the preferred combustion system 40, the micro turbine generator 80is used in combination with a gas storage system 85 and an eductor (notshown). The storage system 85 will utilize the process of a Main, Regen,Guard method with pressurized storage vessels. The Main Vessel is fullypressurized, the Regen Vessel is currently being compressed, and theGuard Vessel is on standby which is either pressurized or unpressurizedas it is on guard. The use of this method allows for an intermittentsource of fugitive emissions to become continuous or steady-state byusing pressurized vapor at all times with the use an eductor to supplynatural gas for clean combustion in a micro turbine, which is oftenincorporated on the same skid as the calorimeter and density meter 105shown in the figure. The eductor will utilize higher pressure naturalgas typically found at 80-120 psig (typical delivered LP pipelinenatural gas) to create a venturi effect for dispersion of vapor andnatural gas. This eductor will also be sized accordingly to meet theinlet pressure requirements of the micro turbine. The natural gas andpressurized vapor will be controlled via flow control valves 75 toensure proper mixing or ratio for clean combustion. In addition, acalorimeter and density meter (BTU Analyzer) 105 may be used todetermine the proper mixture for clean combustion by measuring theHigher Heating Value (HHV) and Wobble Index of the pressurized vapor andthe mixture of natural gas and vapor in the common fuel header. Thecombustion mixture needs to meet the needs of clean combustion for themicro turbine to work efficiently. This mixture is based on the samplegas from pressurized vapor and sample gas of the resultant mixture ofnatural gas and vapor in the common fuel header. The samples are drawnfrom the sample lines 65 shown in FIG. 1 .

The fuel mixture 95 is then routed to the inlet of the micro turbinegenerator 80 which has a detonation arrestor and an inlet fuel shut offvalve for safety. The fuel mixture 95 comprises 30-45% natural gasmaking it suitable for combustion. This type of testing in combinationwith the use of a microturbine can result in 99% VOC destruction. Theelectricity generated from the generator 80 can be recirculated backinto the system 10 to power other components, energy storage, or can besold back to the power grid 120.

Turning to FIG. 2 , a table is shown comparing the efficiencies inconverting the vapor byproduct into electricity. This table shows thedifferent scenarios of various fugitive emissions sources when loaded ata terminal, facility, or refinery, and the potential electricity supplyto the grid. In all cases, there is an overall efficiency gaincomparatively to existing technologies as this is considered a wastestream. This efficiency gain was calculated by the net energy into thesystem over the net energy out of the system.

In yet another embodiment, the disclosed system 10 includes a heatrecovery system 100 operable to perform heat recovery from the exhaustgases released from the generator 80. The heat recovery system includesa heat pump 110 operatively coupled a continuous emission monitoringsystem (CEMS) analyzer 115. The CEMS analyzer 115 can be used to analyzeexhaust emissions from the generators of the system to ensure compliancewith environmental emission standards. For embodiments using a microturbine as the generator, the micro turbine also produces hightemperature exhaust gas which can be used for combined heat and power,after-treatment (Catalytic Converters, Scrubber, Urea Injection, CarbonCapture), or bypassed to atmosphere. The combined heat and power methodhas several options by using a heat exchanger to produce hot water,generate additional electricity using the Organic Rankin Cycle, orusable heat for a drying process.

The invention is not limited to the illustrative embodiments, andencompasses variations and alterations of these embodiments. Althoughthe present invention has been illustrated and described herein withreference to preferred embodiments and specific examples thereof, itwill be readily apparent to those of ordinary skill in the art thatother embodiments and examples may perform similar functions and/orachieve like results. All such equivalent embodiments and examples arewithin the spirit and scope of the present invention, are contemplatedthereby, and are intended to be covered by the following claims. For thepurposes of promoting an understanding of the principles of theinvention, reference has been made to the preferred embodimentsillustrated in the drawings, and specific language has been used todescribe these embodiments. However, this specific language intends nolimitation of the scope of the invention, and the invention should beconstrued to encompass all embodiments that would normally occur to oneof ordinary skill in the art. The particular implementations shown anddescribed herein are illustrative examples of the invention and are notintended to otherwise limit the scope of the invention in any way. Forthe sake of brevity, conventional aspects of the system (and componentsof the individual operating components of the system) may not bedescribed in detail. Furthermore, the connecting lines, or connectorsshown in the various figures presented are intended to representexemplary functional relationships and/or physical or logical couplingsbetween the various elements. It should be noted that many alternativeor additional functional relationships, physical connections or logicalconnections may be present in a practical device. Moreover, no item orcomponent is essential to the practice of the invention unless theelement is specifically described as “essential” or “critical”. Numerousmodifications and adaptations will be readily apparent to those skilledin this art without departing from the spirit and scope of the presentinvention.

What is claimed is:
 1. A vapor recovery system comprising: a feedingsystem operatively coupled to a combustion system, said feeding systemcomprising a plurality of vapor byproduct sources capable of producing avapor of volatile organic compounds, and a gas liquid separator operableto separate liquids and particulates from said vapor to create apurified vapor, said combustion system comprising a compressor, anatural gas supply, a gas storage system, and a generator, wherein saidcompressor is operable to pressurize said purified vapor to a pressurein the range of 50-75 PSIG to form a fully pressurized vapor, whereinsaid gas storage system comprises three pressurized storage containersconfigured to operate interchangeably to provide a steady state of saidfully pressurized vapor to said generator, wherein a first container isfully pressurized to 50-75 PSIG, a second container is under compressionby said compressor, and a third container is either pressurized orunpressurized, wherein each of said containers is fluidly connected tosaid compressor and said generator, wherein said first container isconfigured to feed said generator with said fully pressurized vapor,wherein said second container is operable to serve as a fullypressurized container to feed said generator with said fully pressurizedvapor when said first container becomes depressurized, and wherein saidthird container is operable to serve as a fully pressurized container tofeed said generator with said fully pressurized vapor when said firstand said second container are depressurized, wherein said natural gassupply is operable to enrich said purified vapor with natural gas toform a fuel mixture, said fuel mixture comprising 30-45% natural gas,and said generator operable for converting said fuel mixture intoelectricity.
 2. The system of claim 1 wherein said generator is amicroturbine.
 3. The system of claim 1, further comprising a calorimeterand density meter operable to determine if said fuel mixture will allowfor destruction of ninety-nine percent (99%) of said purified vapor bysaid generator.
 4. The system of claim 3, further comprising acontinuous emission monitoring system analyzer operable to analyzeexhaust emissions from said microturbine.
 5. The system of claim 1,further comprising a heat recovery system operable to convert exhaustgas from said generator into reusable energy.
 6. The system of claim 5wherein said heat recovery system comprises a heat pump.
 7. A method forconverting a vapor of volatile organic compounds into reusable energy,said method comprising the steps of: separating liquids and particulatesfrom said vapor of volatile organic compounds to create a purifiedvapor; compressing said purified vapor to a pressure in the range of50-75 PSIG to form a fully pressurized vapor; storing said fullypressurized vapor in a gas storage system, wherein said gas storagesystem comprises three pressurized storage containers configured tooperate interchangeably to provide a steady state of fully pressurizedvapor to a generator, wherein a first container is fully pressurized to50-75 PSIG, a second container is under compression by a compressor, anda third container is either pressurized or unpressurized, wherein eachof said containers is fluidly connected to said compressor and saidgenerator, wherein said first container is configured to feed saidgenerator with said fully pressurized vapor, wherein said secondcontainer is operable to serve as a fully pressurized container to feedsaid generator with said fully pressurized vapor when said firstcontainer becomes depressurized, and wherein said third container isoperable to serve as a fully pressurized container to feed saidgenerator with said fully pressurized vapor when said first and saidsecond container are depressurized, a natural gas supply is operable toenrich said purified vapor with natural gas to form a fuel mixture,enriching said fully pressurized vapor with natural gas from saidnatural gas supply to form the fuel mixture comprising 30-45% naturalgas; and combusting said fuel mixture in said generator to createelectricity.
 8. The method of claim 7 wherein said generator is amicroturbine.
 9. The method of claim 8, further comprising the step ofproviding a heat recovery system operatively coupled to saidmicroturbine.
 10. The method of claim 9, further comprising the stepconverting an exhaust gas from said microturbine into reusable energyusing said heat recovery system.